Electrosurgical Instrument with a Knife Blade Lockout Mechanism

ABSTRACT

An electrosurgical forceps is provided with a shaft that extends from a housing of the electrosurgical forceps. An end effector assembly operably coupled to the shaft includes a pair of first and second jaw members. One or both of the first and second jaw members is movable from an open configuration, to a clamping configuration. A knife blade assembly includes a knife blade translatable within the first and second jaw members. A knife blade lockout mechanism is in operative communication with the knife blade assembly and includes an elongated cam slot with a cam pin translatable therein from a distal end of the elongated cam slot corresponding to the knife blade lockout mechanism engaged with the knife blade assembly, to a proximal position corresponding to the knife blade lockout mechanism disengaged from the knife blade assembly.

BACKGROUND

1. Technical Field

The present disclosure relates to an electrosurgical instrument and,more particularly, to an electrosurgical instrument including jawmembers and a knife blade lockout mechanism that is configured toprevent unintentional deployment of a knife blade when the jaw membersare in a spaced-apart configuration.

2. Description of Related Art

Electrosurgical forceps are well known in the medical arts. For example,an electrosurgical endoscopic forceps is utilized in surgicalprocedures, e.g., laparoscopic surgical procedure, where access totissue is accomplished through a cannula or other suitable devicepositioned in an opening on a patient. The endoscopic forceps,typically, includes a housing; a handle assembly including a movablehandle; a drive assembly; a shaft; a cutting mechanism such as, forexample, a knife blade assembly; and an end effector assembly attachedto a distal end of the shaft. The end effector includes jaw members thatoperably communicate with the drive assembly to manipulate tissue, e.g.,grasp and seal tissue. Typically, the endoscopic forceps utilizes bothmechanical clamping action and electrical energy to effect hemostasis byheating the tissue and blood vessels to coagulate, cauterize, seal, cut,desiccate, and/or fulgurate tissue. Typically, subsequent to effectinghemostasis, a knife blade of the knife blade assembly is deployed tosever the effected tissue.

Conventional endoscopic forceps, typically, utilize a safety bladelockout mechanism that prevents the blade from being unintentionallydeployed. In particular, an endoscopic forceps may be configured toutilize a direct interaction between a lever and a trigger (or viaanother linkage in the lever mechanism) on the handle assembly toprevent the knife blade from being unintentionally deployed. That is,the knife blade is prevented from moving or translating into a knifeslot on one or both of the jaw members. Under certain surgicalscenarios, however, such as, for example, when the lever is in a“latched” configuration (i.e., the knife blade is operable to severtissue) and a thick bundle of tissue is positioned between the jawmembers, there exists a possibility of the knife blade deploying andwandering or drifting out of the knife slot(s) on the jaw member(s) andbecoming trapped between the jaw members when they are moved to theclamping configuration. This condition is commonly referred to in theart as “blade trap.” As can be appreciated, “blade trap” may cause acutting edge of the knife blade to ineffectively sever electrosurgicallytreated tissue, i.e., the knife blade may not fully or “swiftly” severthe electrosurgically treated tissue.

SUMMARY

Aspects of the present disclosure are described in detail with referenceto the drawing figures wherein like reference numerals identify similaror identical elements. As used herein, the term “distal” refers to theportion that is being described which is further from a user, while theterm “proximal” refers to the portion that is being described which iscloser to a user. As used herein, electrosurgical energy refers to,without limitation, electrical energy, ultrasonic energy, thermal energyand/or mechanical energy used in combination with one of theaforementioned other energies.

According to an aspect of the invention disclosure, an electrosurgicalforceps is provided. The electrosurgical forceps includes a shaft thatextends from a housing of the electrosurgical forceps. A longitudinalaxis is defined through the shaft. An end effector assembly operablycoupled to a distal end of the shaft includes a pair of first and secondjaw members. One or both of the first and second jaw members is movablefrom an open configuration, to a clamping configuration. A knife bladeassembly includes a knife blade that is translatable within the firstand second jaw members when the first and second jaw members are in theclamping configuration to sever tissue. A knife blade lockout mechanismis in operative communication with the knife blade assembly. The knifeblade lockout mechanism includes an elongated cam slot with a cam pintranslatable therein. The cam pin is translatable within the elongatedcam slot from a distal end of the elongated cam slot corresponding tothe first and second jaw members being in the open configuration and theknife blade lockout mechanism engaged with the knife blade assembly, toa proximal position corresponding to the first and second jaw membersbeing in the clamping configuration and the knife blade lockoutmechanism disengaged from the knife blade assembly.

In accordance with the instant disclosure, when the knife blade lockoutmechanism is engaged with the knife blade assembly, the knife bladeassembly is prevented from translating within the first and second jawmembers, and when knife blade lockout mechanism is disengaged from theknife blade assembly the knife blade is capable of translating withinthe first and second jaw members. In certain instances, when the knifeblade lockout mechanism is engaged with the knife blade assembly, theknife blade lockout mechanism could be used to limit the travel of theknife blade assembly. In this instance, the knife blade assembly coulddeploy partially, but not beyond a “safe” distance where the knife bladeassembly is at risk of becoming trapped between the first and second jawmembers. As can be appreciated, this may prevent a surgeon from becomingfrustrated (or confused) that the knife blade assembly cannot bedeployed and would maintain partial functionality of the knife bladeassembly even on thick tissue.

In accordance with the instant disclosure, the knife blade lockoutmechanism may include a generally rectangular configuration having openleading and trailing ends. In certain instances, the open leading endmay be configured to selectively engage a notched portion of the knifeblade assembly. Moreover, a protrusion may be disposed adjacent the opentrailing end of the knife blade lockout mechanism and may be configuredto selectively engage a notched portion of the knife blade assembly.

In certain instances, the knife blade lockout mechanism may be operablypositioned between the first and second jaw members. In this particularinstance, the first and second jaw members may be pivotably coupled toone another via a pivot pin extending through the knife lockoutmechanism and the shaft. Moreover, the earn pin disposed within theelongated cam slot may be disposed within respective cam slots of thefirst and second jaw members and operably coupled to a drive tube of theelectrosurgical forceps to move the first and second jaw members fromthe open position to the clamping position. In this instance, the knifeblade lockout mechanism may be pivotable about the pivot pin to provideselective engagement between the knife blade lockout mechanism and theknife blade assembly.

In certain instances, the knife blade lockout mechanism may bepositioned proximal to the first and second jaw members. In thisparticular instance, the first and second jaw members may be pivotablycoupled to one another via a pivot pin extending through the shaft.Moreover, the cam pin disposed within the elongated cam slot of theknife blade lockout mechanism may be disposed within respective camslots of the first and second jaw members. The cam pin may be operablycoupled to a drive tube of the electrosurgical forceps to move the firstand second jaw members from the open position to the clamping position.

In certain instances, the knife blade lockout mechanism may bepositioned proximal to the first and second jaw members. In thisparticular instance, the first and second jaw members may be pivotablycoupled to one another via a first pivot pin extending through theshaft. A second pivot pin extending through the knife blade lockoutmechanism is positioned within a pair of slots defined through the drivetube such that the knife blade lockout mechanism pivots about the secondpivot pin when the drive tube is actuated. Distal ends of the pair ofslots defined in the drive tube may function as a hard stop for thefirst and second jaw members to provide a predetermined gap distancebetween the first and second jaw members when the first and second jawmembers are in the clamping position. A knife blade assembly returnspring that is configured to return the knife blade assembly to aninitial retracted position may be operably coupled to the knife bladeassembly.

According to another aspect of the instant disclosure, anelectrosurgical forceps is provided. The electrosurgical forcepsincludes shaft that extends from a housing of the electrosurgicalforceps. A longitudinal axis is defined through the shaft. An endeffector assembly operably coupled to a distal end of the shaft includesa pair of first and second jaw members. One or both of the first andsecond jaw members is movable from an open configuration, to a clampingconfiguration. A knife blade assembly includes a knife blade that istranslatable within the first and second jaw members when the first andsecond jaw members are in the clamping configuration to sever tissue. Aknife blade lockout mechanism is selectively engageable with the knifeblade assembly to lock the knife blade in an initial retracted position.The knife blade lockout mechanism is configured to allow passage of theknife blade assembly therethrough. The knife blade lockout mechanismincludes an elongated cam slot with a cam pin translatable therein. Thecam pin is translatable within the elongated cam slot from a distal endof the elongated cam slot corresponding to the first and second jawmembers being in the open configuration and the knife blade lockoutmechanism engaged with the knife blade assembly, to a proximal positioncorresponding to the first and second jaw members being in the clampingconfiguration and the knife blade lockout mechanism disengaged from theknife blade assembly.

In accordance with the instance application, the knife blade lockoutmechanism may include a generally rectangular configuration having openleading and trailing ends, wherein at least one of the open leading andtrailing ends is configured to selectively engage a notched portion ofthe knife blade assembly. In certain instances, the knife blade lockoutmechanism may be operably positioned between the first and second jawmembers.

In certain instances, the knife blade lockout mechanism may be operablypositioned between the first and second jaw members. In this particularinstance, the first and second jaw members may be pivotably coupled toone another via a pivot pin extending through the knife lockoutmechanism and the shaft. Moreover, the cam pin disposed within theelongated cam slot may be disposed within respective cam slots of thefirst and second jaw members and operably coupled to a drive tube of theelectrosurgical forceps to move the first and second jaw members fromthe open position to the clamping position. In this instance, the knifeblade lockout mechanism may be pivotable about the pivot pin to provideselective engagement between the knife blade lockout mechanism and theknife blade assembly.

In certain instances, the knife blade lockout mechanism may bepositioned proximal to the first and second jaw members. In thisparticular instance, the first and second jaw members may be pivotablycoupled to one another via a pivot pin extending through the shaft.Moreover, the cam pin disposed within the elongated cam slot of theknife blade lockout mechanism may be disposed within respective camslots of the first and second jaw members. The cam pin may be operablycoupled to a drive tube of the electrosurgical forceps to move the firstand second jaw members from the open position to the clamping position.

In certain instances, the knife blade lockout mechanism may bepositioned proximal to the first and second jaw members and the firstand second jaw members may be pivotably coupled to one another via afirst pivot pin extending through the shaft. In this particularinstance, a second pivot pin extending through the knife blade lockoutmechanism is positioned within a pair of slots defined through the drivetube such that the knife blade lockout mechanism pivots about the secondpivot pin when the drive tube is actuated. Distal ends of the pair ofslots defined in the drive tube may function as a hard stop for thefirst and second jaw members to provide a predetermined gap distancebetween the first and second jaw members when the first and second jawmembers are in the clamping position. A knife blade assembly returnspring that is configured to return the knife blade assembly to aninitial retracted position may be operably coupled to the knife bladeassembly.

BRIEF DESCRIPTION OF THE DRAWING

Various embodiments of the present disclosure are described hereinbelowwith references to the drawings, wherein:

FIG. 1 is a perspective view of an endoscopic electrosurgical forcepsaccording to an embodiment of the present disclosure;

FIG. 2 is a partial, perspective view of the endoscopic electrosurgicalforceps with a housing thereof removed to illustrate a front-endassembly including a shaft, a drive tube, knife blade lockout mechanismand a blade return spring;

FIG. 3 is a partial, perspective view of the front-end assembly depictedin FIG. 2 with the shaft removed to illustrate the drive tube and knifeblade lockout mechanism;

FIG. 4 is partial, perspective view of a knife blade assembly includingthe knife blade lockout mechanism operably coupled thereto and in anengaged configuration;

FIG. 5 is a partial, cross-sectional view of the shaft, drive tube,knife blade lockout mechanism, knife blade assembly and blade returnspring with the knife blade lockout mechanism in the engagedconfiguration;

FIG. 6 is partial, perspective view of the knife blade assemblyincluding the knife blade lockout mechanism operably coupled thereto andin a disengaged configuration;

FIG. 7 is a partial, cross-sectional view of the shaft, drive tube,knife blade lockout mechanism, knife blade assembly and blade returnspring with the knife blade lockout mechanism in the disengagedconfiguration;

FIG. 8 is a partial, perspective view of the knife blade assembly andblade lockout mechanism in the disengaged configuration with a knifeblade member of the knife blade assembly in a deployed position;

FIG. 9 is a perspective view of an end effector depicted in FIG. 1 witha knife blade lockout mechanism according to an alternate embodiment ofthe present disclosure;

FIG. 10 is a perspective view of the knife blade lockout mechanismdepicted in FIG. 9;

FIG. 11 is a perspective view of the knife blade lockout mechanism shownin an engaged configuration;

FIG. 12 is a side view of the end effector depicted in FIG. 9 with theknife blade lockout mechanism shown in the engaged configuration;

FIG. 13 is a side view of the end effector depicted in FIG. 9 with theknife blade lockout mechanism shown in a disengaged configuration;

FIG. 14 is a perspective view of an end effector with a knife bladelockout mechanism according to another embodiment of the presentdisclosure;

FIG. 15 is a perspective view of the knife blade lockout mechanismdepicted in FIG. 14;

FIG. 16 is a side view of the end effector depicted in FIG. 14 with theknife blade lockout mechanism shown in the engaged configuration; and

FIG. 17 is a partial, side view of the end effector depicted in FIG. 14with the knife blade lockout mechanism shown in a disengagedconfiguration.

DETAILED DESCRIPTION

Detailed embodiments of the present disclosure are disclosed herein;however, the disclosed embodiments are merely examples of thedisclosure, which may be embodied in various forms. Therefore, specificstructural and functional details disclosed herein are not to beinterpreted as limiting, but merely as a basis for the claims and as arepresentative basis for teaching one skilled in the art to variouslyemploy the present disclosure in virtually any appropriately detailedstructure.

Turning now to FIG. 1, an electrosurgical endoscopic forceps 2configured for use with a knife blade lockout mechanism 40 (mechanism40, see FIG. 3) is illustrated. Forceps 2 is provided having alongitudinal axis “A-A” defined therethrough, a housing 4, a handleassembly 6, a rotating assembly 8, a trigger assembly 10 and an endeffector assembly 12. Forceps 2 further includes a shaft 14 having adistal end 16 configured to mechanically engage end effector assembly 12and a proximal end 18 that mechanically engages housing 4. Forceps 2also includes electrosurgical cable 20 that connects forceps 2 to agenerator (not shown) or other suitable power source, although forceps 2may alternatively be configured as a battery powered instrument. Cable20 includes a wire (or wires) (not explicitly shown) extendingtherethrough that has sufficient length to extend through shaft 14 inorder to provide electrosurgical energy, e.g., electrical energy, to oneor both of a pair of jaw members 22 and 24 of end effector assembly 12.In certain embodiments, the jaw members 22 and 24 may be configured totreat tissue with ultrasonic energy, thermal energy, mechanical energyor combinations thereof. Additionally, while the mechanism 40 isdescribed herein configured for use with an endoscopic forceps 2, it iswithin the purview of the present disclosure to configure the mechanism40 for use with open style forceps.

Rotating assembly 8 is rotatable in either direction about longitudinalaxis “A-A” to rotate end effector 12 about longitudinal axis “A-A,” FIG.1.

Housing 4 houses the internal working components of forceps 2, such as adrive assembly (not explicitly shown), working components of the handleassembly 6, electrical raceways associated with the cable 20, and otherworking components therein.

With continued reference to FIG. 1, handle assembly 6 includes a fixedhandle 26 and a moveable handle 28. Fixed handle 26 is integrallyassociated with housing 4 and handle 28 is moveable relative to fixedhandle 26. Moveable handle 28 of handle assembly 6 is ultimatelyconnected to the drive assembly such that, together, handle 28 and driveassembly mechanically cooperate to impart movement of jaw members 22 and24 between a spaced-apart position and a clamping position to grasptissue disposed between sealing surfaces 30 and 32 of jaw members 22,24, respectively. As shown in FIG. 1, moveable handle 28 is initiallyspaced-apart from fixed handle 26 and, correspondingly, jaw members 22,24 are in the spaced-apart position (FIGS. 1-3). Moveable handle 28 isdepressible from this initial position to a depressed position (notexplicitly shown) corresponding to the approximated position of jawmembers 22, 24 (FIG. 8 illustrates the jaw members 22, 24 in a partiallyapproximated position.

With reference again to FIG. 1 and with reference to FIGS. 2, 5 and 7,shaft 14 is illustrated. For illustrative purposes in FIG. 2, thehousing 4 and rotating assembly 8 are removed to better illustrate theshaft 14 and operative components associated therewith. Shaft 14includes a generally elongated configuration and is configured tosupport the jaw members 22, 24 at a distal end 16 thereof via a pivotpin 34 (FIGS. 1-3 and 8). Shaft 14 is also configured to provide passageof a drive tube 38 (FIGS. 2-3 and 5-7) therethrough to move the jawmembers 22, 24 from the spaced-apart position to the clamping position.

Shaft 14 includes a generally elongated slot 15 of suitableconfiguration (FIGS. 2, 5 and 7) to allow the mechanism 40 (or topportion thereof) to pivot therethrough when the mechanism 40 is movedinto engagement with a knife blade assembly 50 (see FIGS. 2 and 5),described in greater detail below.

Drive tube 38 (FIGS. 2-3, 5 and 7) is operably coupled to the driveassembly to effect movement of the jaw members 22, 24 and to move themechanism 40 into and out of engagement with knife blade assembly 50,described in greater detail below. Toward these ends, drive tube 38includes a tubular configuration and couples to the movable handle 28via one or more components including, but not limited to, gears, links,sleeves, etc. (not shown). Drive tube 38 is configured to translatethrough the shaft 14 when the movable handle 28 is moved from itsinitial position to the depressed position. Drive tube 38 couples thejaw members 22, 24 via a cam pin 44 (FIG. 8). In particular, cam pin 44is positioned within respective cam slots 46 and 48 on the jaw members22, 24 (see FIG. 3 in combination with FIG. 8).

Alternately, the jaw members 22, 24 may be opened and closed via alinkage system (not shown) or the like. In this instance, the linkagesystem can be housed within the housing 4 and coupled to the movablehandle 28 by one or more suitable coupling methods to effect movement ofone or both of the jaw members 22, 24.

Drive tube 38 includes a first slot 52 that is in vertical registrationwith the slot 15 on the shaft 14 (FIGS. 5 and 7) to allow the mechanism40 (or top portion thereof) to pivot therethrough when the mechanism 40is moved into engagement with a knife blade assembly 50 (see FIGS. 2-3and 5), described in greater detail below. In certain instance, the camslot 52 may be configured to allow the mechanism 40 to be assembled intothe drive tube 38. As can be appreciated, this can reduce the overallmanufacturing costs of the forceps 2.

Drive tube 38 includes a pair of second slots 54 (FIG. 3 illustrates one(1) of the two (2) slots 54) of suitable configuration that areconfigured to house a pivot pin 56 (FIG. 3) therein such that themechanism 40 is pivotable thereabout when the drive tube 38 istranslated in either the proximal or distal direction. In the embodimentillustrated in FIGS. 1-8, the second slots 54 are oriented approximately90° from the slots 52 and 15 on the respective drive tube 38 and shaft14, and 180° from one another; this facilitates pivoting of themechanism 40 about the pivot pin 56.

In certain instances, a distal end of the second slots 54 may beconfigured to function as a hard stop for the jaw members 22, 24 toprovide a predetermined gap distance between the jaw members 22, 24 whenthe jaw members 22, 24 are in the clamping position.

Continuing with reference to FIGS. 2-8, mechanism 40 is in operativecommunication with the knife blade assembly 50. Mechanism 40 includes agenerally rectangular configuration that compliments the shape of theknife blade assembly 50 (FIGS. 4-8). Mechanism 40 includes open leadingand trailing ends 58 and 60, respectively. Open leading end 58 isconfigured to selectively engage a notched portion 62 of the knife,blade assembly 50 (FIG. 4). To facilitate engagement of the open leadingend 58 with the notched portion 62 of the knife blade assembly 50, theopen leading end 58 includes a finger portion 64 that extends laterallyacross the longitudinal axis “A-A” from a left sidewall 66 of themechanism 40 thus forming a generally “L” shape (FIGS. 4 and 6). Incertain embodiments, such as the embodiments described with respect toFIGS. 9-17, open leading end 58 may include, for example, one or moreother configurations and/or structures to facilitate engagement of theopen leading end 58 with the notched portion 62; a detailed descriptionof these embodiments is discussed below.

Mechanism 40 includes an elongated cam slot 68 having proximal anddistal ends, 70 and 72, respectively (FIGS. 4 and 6). A ramp portion 76(as best seen in FIG. 6) is disposed between the respective proximal anddistal ends 70 and 72 and is configured to pivot the mechanism 40 aboutthe pivot pin 56 when a cam pin 78 that is housed within the cam slot 68comes in contact with the ramp portion 76.

An aperture 77 (shown in phantom in FIG. 4) of suitable proportion isprovided on the mechanism 40 and is configured to receive the pivot pin56 therethrough such that the mechanism 40 is free to pivot thereaboutwhen the cam pin 78 contacts the ramp portion 76.

Cam pin 78 (FIGS. 3-8) is operably coupled to the drive tube 38 via oneor more suitable coupling methods. In the illustrated embodiment, campin 78 is ultrasonically welded to the drive tube 38.

Proximal translation of the drive tube 38 translates the cam pin 78within the elongated slot 68 from the distal end 72 (corresponding tothe jaw members 22, 24 being in the open configuration and the mechanism40 engaged with the knife blade assembly 50, see FIGS. 3 and 4) towardsthe proximal end 70 (corresponding to the jaw members 22, 24 being inthe clamping configuration and the mechanism 40 disengaged from theknife blade assembly, see FIGS. 6 and 8). Prior to the cam pin 78reaching the proximal end 72, the cam pin 78 contacts the ramp portion76, which, in turn, causes the mechanism 40 to pivot about the pivot pin56, which, in turn, causes the finger portion 64 to disengage from thenotched portion 62 of the knife blade assembly 50. With the fingerportion 64 disengaged from the notched portion 62, the knife blade 51 ofthe knife blade assembly 50 is free to translate within a pair of knifeblade channels 53 disposed on the jaw members 22, 24 of the end effector12 (FIGS. 2-3 and 8).

With reference again to FIGS. 2-3 and 8, end effector assembly 12 isdesigned as a bilateral assembly, i.e., where both jaw member 22 and jawmember 24 are moveable about pivot pin 34 relative to one another and toshaft 14. However, end effector assembly 12 may alternatively beconfigured as a unilateral assembly, i.e., where jaw member 24 is fixedrelative to shaft 14 and jaw member 22 is moveable about pivot pin 34relative to shaft 14 and fixed jaw member 24.

The knife blade channels 53 on the jaw members 22, 24 are aligned withthe knife blade assembly 50 to accommodate reciprocation of the knifeblade 52 therethrough when a trigger 11 of the trigger assembly 10 ismoved proximally (FIG. 8).

Knife blade assembly 50 is disposed within shaft 14 and is translatabletherethrough from an initial retracted configuration to an extendedconfiguration into the knife blade channels 53 on the jaw members 22,24. Knife blade assembly 50 includes a generally elongated configurationhaving a split or bifurcated medial portion 55 including two legs 55 aand 55 b defining an opening 57 therebetween that is configured toreceive the pivot pin 56 and cam pin 78 therethrough (FIGS. 4-8). Theopening 57 is configured to permit translation of the knife bladeassembly through the mechanism 40 while allowing the mechanism 40 topivot about the pivot pin 56 and the cam pin 78 to translate within theelongated cam slot 68 when the trigger 11 is moved proximally.

A knife blade assembly return spring 36 (FIGS. 2, 5 and 7) is supportedon the shaft 14. The knife blade assembly return spring 36 is utilizedto return the knife blade assembly 50 including the knife blade 51 tothe initial retracted configuration when the trigger 11 is released.

In use, drive tube 38 is, initially, in an extended configuration andthe jaw members 22 and 24 are an open configuration to receive orposition tissue therebetween (FIGS. 1-3). In this extended configurationof the drive tube 38, the cam pin 78 is positioned at the distal end 72of the elongated cam slot 68 and the finger 64 of the mechanism 40 isengaged with the notched portion 62 of the knife blade assembly 50. Whenthe finger 64 of the mechanism 40 is engaged with the notched portion62, the knife blade assembly 50 including the knife blade 51 isprevented from moving. The unique configuration of the mechanism 40overcomes aforementioned drawbacks discussed above that are typicallyassociated with conventional forceps. In particular, the likelihood ofthe knife blade assembly 50 including the knife blade 51 inadvertentlymoving between the jaw members 22, 24, such as, for example, when largetissue is positioned therebetween, is greatly reduced, if not completelyeliminated. In other words, this greatly reduces, if not completelyeliminates “blade trap” from occurring,

In certain instances, when the mechanism 40 is engaged with the knifeblade assembly 50, the mechanism 40 could be used to limit the travel ofthe knife blade assembly 50. In this instance, for example, the knifeblade assembly 50 could deploy partially, but not beyond a “safe”distance where the knife blade assembly 50 is at risk of becomingtrapped between the jaw members 22, 24. As can be appreciated, this mayprevent a surgeon from becoming frustrated (or confused) that the knifeblade assembly 50 cannot be deployed and would maintain partialfunctionality of the knife blade assembly 50 even on thick tissue.

To move the jaw members 22, 24 toward one another, the movable handle 28is approximated toward the fixed handle 26. Approximation of the movablehandle 28 causes the drive tube 38 to move proximally, which has atwo-fold effect. One, the drive tube 38 moves the cam pin 44 (FIGS. 1and 8) proximally, which, in turn, moves the jaw members 22, 24 towardone another and the clamping configuration. Two, the drive tube 38 movesthe cam pin 78 proximally towards the proximal end 70 until such timethat the cam pin 78 contacts the ramp portion 76, which, in turn, causesthe mechanism 40 to pivot about the pivot pin 56, which, in turn, causesthe finger portion 64 to disengage from the notched portion 62 of theknife blade assembly 50. With the finger portion 64 disengaged from thenotched portion 62, the knife blade 51 of the knife blade assembly 50 isfree to translate within a pair of knife blade channels 53 disposed onthe jaw members 22, 24 of the end effector 12 (FIGS. 2-3 and 8).

With reference to FIGS. 9-14, a mechanism 140 according to an alternateembodiment of the present disclosure is illustrated that may be utilizedwith the forceps 2. Only those operative features that are unique to thefunctionality of the mechanism 140 are described herein.

Unlike mechanism 40 that is positioned proximal with respect to the jawmembers 22, 24, mechanism 140 is positioned between the jaw members 122,124 of the end effector 112 (FIGS. 9, 12 and 13). Moreover, unlikemechanism 40 that utilized its own pivot pin 56 and cam pin 78,mechanism 140 is operably coupled to the pivot pin 134 and cam pin 144that are configured to function in a manner described above (FIG. 9).Further, in the embodiment illustrated in FIGS. 9-14, the elongated camslot 168 is disposed proximal with respect to the aperture 177, i.e.,pivot pin 134 is disposed distal with respect to cam pin 144 (FIG. 10).Finger 64 is replaced by a bottom wall 164 (FIG. 10) that is configuredto engage the notched portion 162 of the knife blade assembly 150.Bottom wall 164 is positioned at the open trailing end 158 as opposed tothe finger 64 that is positioned at the open leading end 60.

In use, the drive tube 38 is, initially, in an extended configurationand the jaw members 122 and 124 are in an open configuration to receiveor position tissue therebetween (FIGS. 9-10 and 12). In this extendedconfiguration of the drive tube 38, the cam pin 144 is positioned at thedistal end 172 of the elongated cam slot 168 and the bottom wall 164 ofthe mechanism 140 is engaged with the notched portion 162 (FIG. 11) ofthe knife blade assembly 150. When the bottom wall 164 of the mechanism140 is engaged with the notched portion 162, the knife blade assembly150 including the knife blade 151 is prevented from moving (FIG. 12).The above described advantages are also achieved with the mechanism 140when compared to conventional forceps.

To move the jaw members 122, 124 toward one another, the movable handle28 is approximated toward the fixed handle 26. Approximation of themovable handle 28 causes the drive tube 38 to move proximally, which hasa two-fold effect. One, the drive tube 38 moves the cam pin 144proximally, which, in turn, moves the jaw members 122, 124 toward oneanother and to the clamping configuration. Two, the drive tube 38 movesthe cam pin 144 proximally towards the proximal end 170 until such timethat the cam pin 144 contacts the ramp portion 176 (FIG. 11), which, inturn, causes the mechanism 140 to pivot about the pivot pin 134, which,in turn, causes the bottom wall 164 to disengage from the notchedportion 162 of the knife blade assembly 150. With the bottom wall 164disengaged from the notched portion 162, the knife blade 151 of theknife blade assembly 150 is free to translate within the pair of knifeblade channels 153 (FIG. 9) disposed in the jaw members 122, 124 of theend effector 112 (FIG. 13).

With reference to FIGS. 14-17, a mechanism 240 according to anotheralternate embodiment of the present disclosure is illustrated that maybe utilized with the forceps 2. Only those operative features that areunique to the functionality of the mechanism 240 are described herein.

Unlike mechanism 140, mechanism 240 includes a protrusion 264 (FIG. 15)that is configured to engage the notch 262 to prevent the knife bladeassembly 250 from moving (FIG. 16). Protrusion 264 includes a generallyarcuate configuration and is positioned at the open trailing end 260. Aslit 265 is provided at a top surface of the protrusion 264 and isconfigured to releasably engage a portion of the notched portion 262(e.g., adjacent the bifurcated leg 255 b) such that a press-fit,friction-fit, etc. is created therebetween. As can be appreciated, thispress or friction-fit facilitates maintaining the protrusion 264 andnotched portion 262 in substantial alignment with one another.

In use, the drive tube 38 is, initially, in an extended configurationand the jaw members 222 and 224 are an open configuration to positiontissue therebetween (FIG. 16). In this extended configuration of thedrive tube 38, the cam pin 244 is positioned at the distal end 272 ofthe elongated cam slot 268 and the protrusion 264 of the mechanism 240is engaged with the notched portion 262 of the knife blade assembly 250(FIG. 16). When the protrusion 264 of the mechanism 240 is engaged withthe notched portion 262, the knife blade assembly 250 (FIG. 14)including the knife blade 251 (FIGS. 16-17) is prevented from moving.The above described advantages are also achieved with the mechanism 140when compared to conventional forceps.

To move the jaw members 222, 224 toward one another, the movable handle28 is approximated toward the fixed handle 26. Approximation of themovable handle 28 causes the drive tube 38 to move proximally, which hasa two-fold effect. One, the drive tube 38 moves the cam pin 244proximally, which, in turn, moves the jaw members 222, 224 toward oneanother and the clamping configuration. Two, the drive tube 38 moves thecam pin 244 proximally towards the proximal end 270 until such time thatthe cam pin 244 contacts the ramp portion 276 (FIG. 16), which, in turn,causes the mechanism 240 to pivot about the pivot pin 234, which, inturn, causes the protrusion 264 to disengage from the notched portion262 of the knife blade assembly 250 (FIG. 17). With the protrusion 264disengaged from the notched portion 262, the knife blade 251 of theknife blade assembly 250 is free to translate within the pair of knifeblade channels (not explicitly shown) disposed in the jaw members 222,224 of the end effector 212 (FIG. 14).

From the foregoing and with reference to the various figure drawings,those skilled in the art will appreciate that certain modifications canalso be made to the present disclosure without departing from the scopeof the same. For example, in certain instances one or more resilientmembers, such as, for example, a spring or the like may be operablycoupled to any of the aforementioned mechanisms 40, 140, 240 tofacilitate pivoting thereof about the respective pivot pins 56, 134,234.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of particular embodiments. Those skilled in the artwill envision other modifications within the scope and spirit of theclaims appended hereto.

What is claimed is:
 1. An electrosurgical forceps, comprising: a housinghaving a shaft extending therefrom; an end effector assembly operablycoupled to a distal end of the shaft and including a pair of first andsecond jaw members, at least one of the first and second jaw membersmovable from an open configuration for positioning tissue therebetween,to a clamping configuration for grasping tissue therebetween; a knifeblade assembly including a knife blade translatable within the first andsecond jaw members when the first and second jaw members are in theclamping configuration; and a knife blade lockout mechanism in operativecommunication with the knife blade assembly, the knife blade lockoutmechanism including an elongated cam slot with a earn pin translatabletherein from a distal end of the elongated cam slot corresponding to thefirst and second jaw members being in the open configuration and theknife blade lockout mechanism engaged with the knife blade assembly, toa proximal position corresponding to the first and second jaw membersbeing in the clamping configuration and the knife blade lockoutmechanism disengaged from the knife blade assembly.
 2. Anelectrosurgical forceps according to claim 1, wherein, when the knifeblade lockout mechanism is engaged with the knife blade assembly, theknife blade is prevented from translating within the first and secondjaw members, and when the knife blade lockout mechanism is disengagedfrom the knife blade assembly the knife blade is capable of translatingwithin the first and second jaw members.
 3. An electrosurgical forcepsaccording to claim 1, wherein the knife blade lockout mechanism includesa generally rectangular configuration having open leading and trailingends.
 4. An electrosurgical forceps according to claim 3, wherein theopen leading end is configured to selectively engage a notched portionof the knife blade assembly.
 5. An electrosurgical forceps according toclaim 3, wherein a protrusion is disposed adjacent the open trailing endof the knife blade lockout mechanism and is configured to selectivelyengage a notched portion of the knife blade assembly.
 6. Anelectrosurgical forceps according to claim 1, wherein the knife bladelockout mechanism is operably positioned between the first and secondjaw members.
 7. An electrosurgical forceps according to claim 6, whereinthe first and second jaw members are pivotably coupled to one anothervia a pivot pin extending through the knife lockout mechanism and theshaft, and wherein the cam pin disposed within the elongated cam slot isdisposed within respective cam slots of the first and second jaw membersand operably coupled to a drive tube of the electrosurgical forceps tomove the first and second jaw members from the open position to theclamping position.
 8. An electrosurgical forceps according to claim 7,wherein the knife blade lockout mechanism is pivotable about the pivotpin to provide selective engagement between the knife blade lockoutmechanism and the knife blade assembly.
 9. An electrosurgical forcepsaccording to claim 1, wherein the knife blade lockout mechanism ispositioned proximal to the first and second jaw members.
 10. Anelectrosurgical forceps according to claim 9, wherein the first andsecond jaw members are pivotably coupled to one another via a pivot pinextending through the shaft, and wherein the cam pin disposed within theelongated cam slot of the knife blade lockout mechanism is disposedwithin respective cam slots of the first and second jaw members and isoperably coupled to a drive tube of the electrosurgical forceps to movethe first and second jaw members from the open position to the clampingposition.
 11. An electrosurgical forceps according to claim 9, whereinthe first and second jaw members are pivotably coupled to one anothervia a first pivot pin extending through the shaft, wherein a secondpivot pin extending through the knife blade lockout mechanism ispositioned within a pair of slots defined through the drive tube suchthat the knife blade lockout mechanism pivots about the second pivot pinwhen the drive tube is actuated.
 12. An electrosurgical forcepsaccording to claim 11, wherein distal ends of the pair of slots definedin the drive tube function as a hard stop for the first and second jawmembers to provide a predetermined gap distance between the first andsecond jaw members when the first and second jaw members are in theclamping position.
 13. An electrosurgical forceps according to claim 1,further comprising a knife blade assembly return spring that isconfigured to return the knife blade assembly to an initial retractedposition.
 14. An electrosurgical forceps, comprising: a housing having ashaft extending therefrom; an end effector assembly operably coupled toa distal end of the shaft and including a pair of first and second jawmembers, at least one of the first and second jaw members movable froman open configuration for positioning tissue therebetween, to a clampingconfiguration for grasping tissue therebetween; a knife blade assemblyincluding a knife blade translatable within the first and second jawmembers when the first and second jaw members are in the clampingconfiguration; and a knife blade lockout mechanism configured to allowpassage of the knife blade assembly therethrough for selectiveengagement with the knife blade assembly to lock the knife blade in aninitial retracted position, the knife blade lockout mechanism includes agenerally rectangular configuration having open leading and trailingends at least one of which configured to selectively engage a notchedportion of the knife blade assembly, the knife blade lockout mechanismincluding an elongated cam slot with a cam pin translatable therein froma distal end of the elongated cam slot corresponding to the first andsecond jaw members being in the open configuration and the knife bladelockout mechanism engaged with the knife blade assembly, to a proximalposition corresponding to the first and second jaw members being in theclamping configuration and the knife blade lockout mechanism disengagedfrom the knife blade assembly.
 15. An electrosurgical forceps accordingto claim 14, wherein the knife blade lockout mechanism is operablypositioned between the first and second jaw members.
 16. Anelectrosurgical forceps according to claim 15, wherein the first andsecond jaw members are pivotably coupled to one another via a pivot pinextending through the knife blade lockout mechanism and the shaft, andwherein the cam pin disposed within the elongated cam slot is disposedwithin respective cam slots of the first and second jaw members andoperably coupled to a drive tube of the electrosurgical forceps to movethe first and second jaw members from the open position to the clampingposition, wherein the knife blade lockout mechanism is pivotable aboutthe pivot pin to provide selective engagement between the knife bladelockout mechanism and the knife blade assembly.
 17. An electrosurgicalforceps according to claim 14, wherein the knife blade lockout mechanismis positioned proximal to the first and second jaw members, wherein thefirst and second jaw members are pivotably coupled to one another via apivot pin extending through the shaft, and wherein the cam pin disposedwithin the elongated cam slot of the knife blade lockout mechanism isdisposed within respective cam slots of the first and second jaw membersand operably coupled to a drive tube of the electrosurgical forceps tomove the first and second jaw members from the open position to theclamping position.
 18. An electrosurgical forceps according to claim 14,wherein the knife blade lockout mechanism is positioned proximal to thefirst and second jaw members, wherein the first and second jaw membersare pivotably coupled to one another via a first pivot pin extendingthrough the shaft, wherein a second pivot pin extending through theknife blade lockout mechanism is positioned within a pair of slotsdefined through the drive tube such that the knife blade lockoutmechanism pivots about the second pivot pin when the drive tube isactuated, wherein a distal end of the slot in the drive tube functionsas a hard stop for the first and second jaw members to provide apredetermined gap distance between the first and second jaw members whenthe first and second jaw members are in the clamping position.
 19. Anelectrosurgical forceps according to claim 14, further comprising aknife blade assembly return spring that is configured to return theknife blade assembly to its initial retracted position.